The frontal lobe region of the brain has been implicated in executive functioning, planning, and premeditation. Individuals with neurological deficits, particularly in executive functioning, are more likely to act impulsively, without premeditation, and without anticipation of the consequences of their actions. It was in part these cognitive deficits that the United States Supreme Court cited in Atkins v. Virginia as a basis for finding the mentally retarded less culpable and therefore categorically exempt from the death penalty.

One of the most frequent uses of neurological and neuropsychological testing is to evaluate executive functioning in defendants charged with first-degree murder. The claim is that because of the Defendant’s limitations in executive functioning, they could not have formed the mental state necessary to commit first-degree murder. Interestingly, the neuropsychological testing introduced in the case today was by a court-appointed expert, who testified that the Defendant was unable to plan or premeditate his actions. The Defendant was nevertheless found guilty of first-degree murder.

Defendant admitted at trial that he shot and killed the victim. The question for the jury was whether the killing was first-degree murder, second-degree murder, voluntary manslaughter or self-defense. The jury found the killing was first-degree murder, which the Defendant argues was reached because of prosecutorial misconduct during closing arguments. Under appointment by the court, a professor of psychiatry testified as an expert in neuropsychology. The expert, Dr. Charles Hinkin, conducted an evaluation of Defendant’s neurocognitive and neuropsychiatric functioning. He determined that Defendant had an IQ of 68, within the mentally retarded range. Defendant performed in the impaired range on tests measuring executive functioning, problem solving, sequencing and the ability to inhibit his behavior. According to Hinkin, “[The Defendant] demonstrated severe psychiatric dysfunction.” Asked how these deficits and disorders affect a person “in the real world in their everyday lives,” Hinkin provided the following assessment. “[P]eople with executive dysfunction have trouble planning. They have troubles anticipating what will happen … or how to solve things. Their problem solving is poor.” They also have trouble with inhibition, an inability “to rein themselves in;” they tend to be impulsive and are prone to “knee-jerk reactions;” they do things “on the spur of the moment without … thinking them through.” People with low IQ’s, Hinkin testified, “often misinterpret things. They don’t size up the situation…. They misinterpret other’s intentions.” The jury nevertheless found the Defendant guilty of first-degree murder. The Los Angeles Superior Court found that there was no prejudice from any prosecutorial misconduct, and affirmed the judgment.

Blog Editor

Nita A. Farahany
Prof. of Law and Philosophy
Prof. of Genome, Sciences and Policy
Duke Law School
*All opinions expressed on this blog are the author's alone and not those of any institution, organization or other entity with which she is affiliated